1. Field of the Invention
This invention relates to the art of medical computer aided detection, and more specifically, to computer aided detection based on a set of medical images.
2. Description of Related Art
Hospital information systems and medical laboratory systems are producing an increasing amount and types of medical image data. Hospitals have gradually replaced conventional clinical charts with electronic clinical charts. Hospitals have added databases of clinical histories and medical prescription histories. Radiology information systems have been added that provide information for aiding diagnosis. More recently, Picture Archiving and Communication Systems (PACS) have been developed as computer systems dedicated to the storage, retrieval, distribution and presentation of the medical image data. PACS are a replacement for hard-copy based means for managing medical images, such as film archives. Full PACS handle images from various modalities, such as ultrasonography, magnetic resonance imaging, position emission tomography, computed tomography, endoscopy, mammography and radiography (plain X-rays).
Computer aided detection (CAD) is currently proving to be an effective means of assisting doctors. For example, CAD has been useful in assisting doctors with patients having late stage illnesses. Algorithms for CAD are being developed and refined for an increasing number of diseases and illnesses.
A typical PACS network may consist of a central server which stores a database containing images. The central server may be connected to clients in a LAN or WAN, as well as over the Internet. Client workstations can include local peripherals for scanning image films into the system (e.g., film digitizer), printing image films from the system and interactive display of digital images. PACS workstations offer means of manipulating the images (crop, rotate, zoom, brightness, contrast, etc.).
Many types of imaging equipment, i.e. modalities, are becoming capable of feeding patient images directly to the PACS in digital form. A set of standards for storing and transmitting medical images have been developed known as Digital Imaging and Communications in Medicine (DICOM), a NEMA standard. DICOM has been developed to enable integration of scanners, servers, workstations, printers and network hardware from multiple vendors. Thus DICOM provides a common platform for a large number of modalities. DICOM includes both a file format definition and a network communications protocol for transmission of images.
The DICOM file format contains both a header and image data. The header can contain standardized fields and free-form fields. DICOM files contain required elements, which are dependent on the image type (i.e., corresponding to a modality).
A patient visit to a hospital or other medical practice can result in a study made including data obtained for a modality that may provide one or more image files. Several patient visits can result in several studies. A PACS system is typically capable of storing and managing image files for many patients. CAD algorithms are continuously being developed that can perform detection using medical images. However, there is a need for a system that can provide the large number of medical images of patients to the CAD algorithms to perform diagnosis. In particular, a system is desirable that can provide detection services for hundreds of patients, for many different potential diseases using an evolving variety of CAD software. Over a long term, a system serving such a role needs to adapt to a varying number and types of images and varying demand for detection services, be easily expanded to new or modified CAD software, and be capable of scaling up to handle an increasing number of patient studies.